The present invention relates generally to the transfer of discrete sheets. More particularly, this invention is directed toward providing improved methods and apparatus for transporting laminated media sheets of varying length from a printer to a separated processing apparatus as well as approaches for facilitating alignment of the printer and processing apparatus to enhance such sheet transfer.
In the graphics arts field, it is extremely important that so-called master images of the original objects being reproduced in a prepress operation be free of visually discernible image defects that would impact negatively in the formation of commercially acceptable prints. The master images are, in turn, used in the subsequent formation of either positive or negative copies, depending on the platemaking process employed. Since the final printed image will only be as good as its master image, considerable efforts are undertaken to produce only the highest quality master.
A recent development in the image forming arts has achieved high quality, high resolution images, such as radiological images of the medical type, without the need for silver halide film and processing techniques along with their attendant equipment and chemical processing issues. In this regard, high quality and high resolution images have been produced by a dry process imaging process which uses laser beams imaging on a thermographic image forming medium. Examples of this kind of thermographic image forming medium are described in commonly assigned International Patent Application No. PCT/US 87/03249 published Jun. 16, 1988, under International Publication Number WO 88/04237; and U.S. Pat. No. 5,200,297. After this laminate has been imaged, it is delaminated by peeling one layer therefrom and having the remaining imaged media relaminated with a protective coating. For a more detailed description of the imaging technique and an associated peeling process, reference is made to commonly assigned U.S. Pat. Nos.: 5,141,584 to Schuh et al and 5,159,352 to Ferla et at. The print engine or thermal laser imaging device for imaging laminates of the thermographic type operate to imagewise expose them by virtue of a laser printer. These thermographic prints are relatively flexible, yet are stiff and therefore present special considerations during handling thereof. For instance, these laminates are prone to peel or delaminate along their edges if handled incorrectly. Such undesired or premature delaminations might alter impermissably the desired image or otherwise affect their subsequent processing. Also, in the graphics prepress field, there is a requirement for printing sheets of varying dimensions so that transferring them from a printer to a separate processor can present problems.
It has been determined that in handling discrete sheets of media of different sizes, there is a possibility of undesirable crumpling or curling. Not only does the crumpling and curling affect adversely the subsequent sheet feeding in an orderly manner, but it may damage the particular sheets involved. This tendency for crumpling can be troublesome when handling thermographic laminates of the above type because the latter might delaminate prematurely along the edges, thereby impermissably altering the printed image. The situation is also aggravated because in certain situations longer sheets being transferred may curl and fold over in a manner such that their trailing edge is located adjacent their leading edge, thereby inhibiting proper feeding. Accordingly, there are continuing efforts to improve upon the transfer of the printed laminar media sheets, especially those having varying lengths in a manner for minimizing their crumpling, curling, damage, and misfeeding. Moreover, there is a desire to easily align the processor with the printer for facilitating the desired transfer of the printed laminates.